The camera is jerky and the sound tinny, but this video gives some idea of the energy at Barack Obama's pre-election rally last night. The crowd was deafening. The line began forming three hours prior to the event, in 30 degree weather. The journalists covering the speech kept pulling out their personal cameras to snap photos: Somehow, this run of his, these crowds of his, feel historic. Or so the reporters murmur. The words "Bobbie Kennedy" float up dozens of times a night from onlookers old enough to remember him. Obama's speech underwent another subtle shift, too. There was much more emphasis placed on the word "progressive," a much more explicit recognition of Obama's potential meaning to a particular ideological movement. He spoke of "Independents who recognize that the current course we're on is not working, and are ready to form a coalition with Democrats for progressive change," chided the observers who said there was no way all these diverse individuals would turn out "for a progressive Democrat." I've not heard that word so oft-repeated at his rallies before. Indeed, the whole speech seemed the product of Obama's thinking about how he could use his political potency to shift the center in America to the left. "We will send a message," he said, "that we will not only end the war in Iraq, not only bring our troops home, but we will change the mindset that got us into that war in the first place." In some ways, it's that grandeur of ambition that separates Obama from Clinton Even before he said so explicitly, many progressives I know spoke of his ability not to change policies, but to change minds -- to do for progressivism what Reagan did for conservatism. Clinton, they agreed, was competent and well-meaning, but lacked that potential. The crowd was, as always, young. One element of Obama's appeal to young people that has not garnered much attention is his speech patterns. Not the oratorical brilliance he demonstrates on the stump, but the slang. There was something undeniably powerful about watching him lean into the microphone the night he won the Iowa Caucus and saying, "Give it up for my wife Michelle!" Politicians don't say "give it up." My generation does. They also don't say, by way of greeting, "what's going on?" And they shake hands, they don't, as Obama often does, slap into a clasp linked around the thumbs. There have been many politicians with undeniable appeal to the young. Howard Dean. Ron Paul. At one point, John McCain. But none of them have been recognizable to the young. Obama is. And, as we're seeing in the rallies, and the Caucus totals, that matters.